PANAMA'S VOLUBLE president, Gen, Omar Torrijos, now says in an interview that he would let the United States help guarantee the canal's neutrality after it passes back under Panamanian control. This concession would seem to address the United States prime demand in negotiations for a new treaty to replace the grossly unjust treaty that Teddy Roosevelt imposed in 1903. That demand is that when the new treaty expires, presumably around the year 2000, Washington will still have a role in the defense of the canal.

Will the general's negotiators speel out privately and officially, in the talks resuming here today, what he has hinted publicly? Will American negotiators be ready to offer matching concessions? If so, the Carter administration may be closer to a resolution of the corrosive Panama issue than at any point since talks began . . . in 1964. The diplomatic prize glitters. But experience counsels caution, for this is not a matter that can be handled in cozy exchanges between diplomats; in both countries the issue is deeply rooted in domestic politics.

Gen. Torrijos's reported readiness to compromise may not arise exclusively, as he suggests, from deference to his Latin neighbors. It may also arise from his need to reassure the numerous Panamanians who, lacking full confidence in the general and perhaps also in themselves, hesitate to take the full burden of the canal upon Panama. The threat to Panamanian ratification of a new treaty has always come less from the radical left than the conservative right.

In this country, the rights has widely promoted the wrongheaded notion that the Canal Zone is American sovereign territory that should not be "given away" to Panama. In fact, the 1903 treaty bestowed "rights in perpetuity . . . as if [the United States] were the sovereign." It is these rights - as distinct from actual sovereignty, which technically was never surrendered by Panama - that would be returned on agreed terms in a new tready. But "retention" of a "sovereignty" that the United States never truly acquired has become, to many Americans, a point of profound national honor and pride.

Some new polls indicate that popular support for "retention? is growing. By one Senate vote count, there are at least 43 relatively hard votes lined up against a new treaty, even one embodying the concession hinted at by Gen. Torrijos. If Mr. Carter is serious about pressing for anew treaty, he must prepare for what will unquestionably be the most wracking political combat of his new administration.